9/25/2015 1
A linear programming model to optimize diets in environmental policy scenarios Moraes, L.E. et al.(2012)
Katarina Nielsen Dominiak Department of Large Animal Sciences
Introduction
Global food demands increase -> more animal products will be produced Carbohydrate fermentation (from forage) in dairy cattle produces CH4 Protein, starch and minerals in feed can lead to excretion of N and minerals if fed at higher levels than animal requirements 72% of total emitted CH4 in Brazil was from enteric fermentation (1994)
K.N. Dominiak, AQMHM 2015 Department of Large Animal Sciences
Introduction
Greenhouse gas (GHG), NO3-, and minerals contaminate the environment Policies and legislations formulated to limit environmental impacts of livestock production
- Clean Water Act (US EPA 2003)
- Manure applied to crops and pastures at levels the
plants can extract (Nitrate,Phosporous)
- Kyoto Protocol reduces GHG to level of 1990
- Carbon markets in Europe (and the States)
K.N. Dominiak, AQMHM 2015 Department of Large Animal Sciences
Problem
Mandatory carbon (CH4) emission policies might be the future Two policies are discussed:
- Limit the quantity of CH4 emitted
- Require emission taxes
A precise diet formulation and balance will meet BOTH animal nutritient requirements AND decrease environmental impacts of animal agriculture
K.N. Dominiak, AQMHM 2015 Department of Large Animal Sciences
Aim
Reduce CH4 emission and excretion of N and minerals Optimal diet cost and feed selection Joint optimization of costs and emisions+excretions Linear programming: A method to achieve best outcome given certain constraints Constraints are represented by linear relationships
K.N. Dominiak, AQMHM 2015 Department of Large Animal Sciences
Three scenarios – three models
BASEM: Cheapest possible feed – No GHG policies (baseline) TAXM: Effect of tax on diet costs and composition, emission and excresion Computes optimal feed input mix that balances off tax savings for lower emissions REDM: Feed costs vs emission and excresion if forced to reduce CH4 emission Decision variables like BASM but with the extra constraint
K.N. Dominiak, AQMHM 2015 Department of Large Animal Sciences
Constraints: Nutrient requirements Defined feed limits Fibre proportions Decision variables: Available feed and their costs